Six Questions on Compiling Qt for MinGW 64 bit

I have been trying to recompile the source code of qt for three days now.
I've got a win 10 64bit laptop and am trying to build qt which compiles with MinGW 64bit
I am trying to do a shadow-build from the source in D:/Qt64/qt-source/qt5 into D:/Qt64/qt-build

it asks me after 15 minutes if I want commercial or opensource--what should I answer?? This is a hobby, not a commercial endeavour.

I start with cmd.exe and run the qt5vars.bat file to modify the PATH each time I open a new cmd.exe window or bash window.
It moves along quite nicely in cmd.exe but freezes after about 1-1/2 hours with :

I am in cmd.exe, using the MS designation "D:/Qt64..... etc" Where did this "/D/Qt64.....etc" depiction come from??
MS cmd.exe doesn't do *.sh shell scripts, does it??

Another time it froze complaining about a missing file .GLES2/gl2.h: No such file or directory compilation terminated.

I restarted config with the -opengl platform option. Is this correct??
Must I install a 64 bit graphics library or something?

Yet another time it froze at sometime in the night after hours of compiling with
fatal error: uiviewsettingsinterop.h: No such file or directory

Should I be using a cmd.exe or a bash window started from my D:/MinGW/msys folder?

When this process crashes after several hours and after I stop crying can I restart the config/make/make install routine and with new parameters and will the whole build resume after the point where it crashed...Or must I start over???

Good Answers. This is good to hear..except for item #2
I was using the microsoft cmd.exe, it's the same as cmd.exe in MinGW, isn't it?
What is cmd.exe supposed to do with a file ending in 'sh'
Did you see the mixed notation in that command line?